This proposal describes a symposium on selected areas of the secretory immune system with particular emphasis on salivary immunity, Streptococcus mutans and dental caries. The overall objective of the symposium is to provide the most current basic information in these areas so that a critical evaluation can logically lead to the initial planning of field trials with an effective S. mutans antigen vaccine in humans. This can best be accomplished by: 1) reviewing the current status of antigen induction of a secretory immune response and the role of T and B cells in gut-associated-lymphoid-tissue (GALT) and bronchial-associated-lymphoid-tissue (BALT) in this response; 2) discussing the latest information on stimulation and homing of IgA precursor cells, biosynthesis and secretion of IgA, the functional role of IgA in disease, and the fate of IgA in the oral cavity; 3) assessing the primate and rodent models and anti-caries immunity in terms of proposed human studies and to compare these models with other well studied diseases affecting mucosal tissue; and 4) describing the recent advances in purification of candidate antigens from S. mutans. Finally the participants, in subgroups, will address the questions of a) candidate antigens and their administration, b) relevance of in vivo and in vitro caries models, and c) initial discussion and plans for caries vaccine trials in humans.